1. Field of the Invention
The invention relates to the production of textile fiber products having a relief-like structure. More particularly, it relates to methods of producing non-woven, composite fabrics or fiber fleeces with boucle-type knobs or ridges on their surface by combining several fiber layers in a batt in special needling and retracting operations.
2. Description of the Prior Art
In the art of producing non-woven fabrics it is known to improve the coherence of fiber fleeces by subjecting a needle-punched batt of different fibers to a retracting operation, whereby the retractable fibers, through their shrinking and/or curling, create a mechanical interlock between the fibers. There are now commercially available a variety of retractable synthetic fibers which, at a certain temperature determined by their physical characteristics, undergo a longitudinal retraction of up to 50 percent. Other available fibers are composed of two individual filaments which have different longitudinal retraction ratios (so-called hetero-fibers) so that the retraction treatment results in a curling or crinkling of the fibers. Those retractable fibers are uniformly intermingled with other, non-retractable or less retractable fibers in a batt of fibers; or separate batts of different fibers are superposed on one another and passed through a needle loom, where the fibers of the two batts are comingled and interlaced.
Generally, this kind of fiber batt, when subjected to a retraction treatment, produces a felt-like fleece with a flat surface. It has not been possible in the past to obtain boucle-type knobs or ridges on the product surface with any of the known methods of producing non-woven fabrics. On the other hand, it has already been suggested to produce non-woven fabrics in such a way that a fiber batt of little-retractable fibers is needled through another fiber batt of highly retractable material. The shortening of the highly retractable fibers causes the punched-through tufts of the other fibers to become clamped and retained between the retracted fibers, so that the protruding ends of the clamped tufts can then be transformed by known procedures (brushing, for example) into a fiber pile. It is not an object of the present invention to suggest a method for producing this kind of surface structure.
A different surface structure is obtained with another prior art method where a soft plastic backing is applied to a needled felt batt of retractable fibers. Retraction treatment of the needled felt causes the backing to wrinkle and to pucker. However, because of its closed plastic backing, the end product has unfavorably modified textile characteristics.
Further suggestions concern themselves with the combination of two fiber webs of unequal retraction ratios, using, for example, a highly retractable woven fabric and a fiber fleece of little-retractable fibers and bonding the two webs together, whereby the adhesive is applied selectively with a pattern drum so as to create a line pattern along which the webs are held together. When this laminate is subjected to the retracting treatment, the shrinkage of the retractable fabric causes the non-retracting fiber fleece to fold upwardly between the bond lines. The result are furls or ridge-like folds, depending on the bonding pattern. The surface structure obtained is of the cloque-type, but the end product is not a very durable one, because no bond exists between the upper and lower web layers in the areas between the bond lines. Furthermore, as it is unavoidable in this case that the line pattern of adhesive application becomes visible, the optical impression made by the product is not a very favorable one.
Still further prior art methods call for stitching operations to create particular surface structures and to interlock the layers of the fabric with endless yarns. Apart from a considerable increase in the cost of production, the products obtained by these methods have the disadvantage that any thread breakage during use causes their appearance and value to decline drastically.